Device for amplifying and sampling high dynamic signals

Abstract

A device is provided for amplifying and sampling signals in an acquisition chain before application thereof to an analog-digital converter and in particular multiplexed signals. It includes two blocking samplers to which a gain of 1, 2 or 16 for the first one and a gain of 2 or 16 for the second one may be applied by selective closure of switches. A switch allows either the input signal or the signal from the second sampler to be applied to the first sampler. Another switch allows the outputs of one or other of the samplers to be connected to the input of a voltage comparator. By a very limited number of comparison steps, gain modifications and possible relooping of the output to the input of the device for one or more reamplifications, an input signal may be given any gain between 2 0 and 2 13 .

What is claimed is: 
     
       1. A device for amplifying and sampling high dynamic signals, issued from a multiplexer, comprising: first and second amplification and sampling means, each associated with a respective feedback network and being capable of taking on selectively several different gain values through control of said feedback network;   voltage comparator means for comparing signals issuing from said first and second amplification and sampling means to predetermined threshold voltages;   commutation means for selectively applying signals which issue from said first and second amplification and sampling means to said voltage comparator means and for selectively controlling said feedback network for changing the gain of said first and second amplification and sampling means; and   selecting means for selectively controlling said commutation means depending on a signal issuing from said voltage comparator means;   said first and second amplification and sampling means including respective sample and hold units disposed in series, the output of a first sample and hold unit being connected permanently to the input of a second sample and hold unit, a respective one of said feedback networks being connected to each of said sample and hold units for providing several predetermined gain values in response to selective closure of said commutation means under the control of said selection means;   said commutation means comprising first switching means for selectively connecting to the input of the voltage comparator means either a voltage issued from the first sample and hold unit or a voltage issued from the second sample and hold unit and second switching means for selectively connecting to the input of the first sample and hold unit either a voltage issued from the multiplexer or a voltage from the second sample and hold unit.   
     
     
       2. The device as claimed in claim 1, wherein the feedback network associated with said first sample and hold means provides an amplification gain of 1, 2 or 16 and the feedback network associated with the second sample and hold means provides an amplification gain of 2 or 16. 
     
     
       3. The device as claimed in claim 2, wherein the commutation means comprises third switching means having switching elements associated with said feedback networks for changing the gain of said amplification and sampling units; the selection means includes means for generating a clock signal, decoder means for generating signals defining successive times within an amplification cycle, a first bistable flip-flop actuated by said clock signal and the signal from said voltage comparator means for generating control signals for said switching elements associated with said feedback networks, a second bistable flip-flop actuated by two signals from the decoder and defining two successive times in said amplification cycle for generating a control signal for said second switching means and for a switching element of said feedback network associated with the first sample and hold unit, a third bistable flip-flop actuated either by two signals from said decoder which represent the first two consecutive times of said amplification cycle or by a signal derived from said clock signal and from the signal coming from said voltage comparator for generating a signal for controlling said first switching means, a signal for controlling the second sample and hold unit and a signal conditioned by said two signals from said decoder which defines the first two consecutive times of said amplification cycle, for controlling the first sample and hold unit. 
     
     
       4. The device as claimed in claim 3, wherein said selection means includes means for storing a value of amplification gain at the end of each amplification cycle, including plural counters for counting signals from the first bistable flip-flop, the enabling input of said counter being connected to an output of said decoder, the outputs of said counters being connected to a storing element for storing a signal representing the value of the amplification gain.